// Copyright 2018-present MongoDB Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <iostream>
#include <list>
#include <numeric>
#include <sstream>
#include <vector>

#include <bsoncxx/builder/basic/array.hpp>
#include <bsoncxx/builder/basic/document.hpp>
#include <bsoncxx/string/to_string.hpp>
#include <mongocxx/client.hpp>
#include <mongocxx/exception/exception.hpp>
#include <mongocxx/exception/logic_error.hpp>
#include <mongocxx/instance.hpp>

// NOTE: Any time this file is modified, a DOCS ticket should be opened to sync the changes with the
// corresponding page on docs.mongodb.com. See CXX-1514, CXX-1249, and DRIVERS-356 for more info.

using namespace mongocxx;

std::string get_server_version(const client &client)
{
    bsoncxx::builder::basic::document server_status{};
    server_status.append(bsoncxx::builder::basic::kvp("serverStatus", 1));
    bsoncxx::document::value output = client["test"].run_command(server_status.extract());

    return bsoncxx::string::to_string(output.view()["version"].get_utf8().value);
}

void aggregation_examples(const mongocxx::client &client, const mongocxx::database &db)
{
    {
        // Start Aggregation Example 1
        using namespace bsoncxx::builder::basic;

        mongocxx::pipeline p{};
        p.match(make_document(kvp("items.fruit", "banana")));
        p.sort(make_document(kvp("date", 1)));

        auto cursor = db["sales"].aggregate(p, mongocxx::options::aggregate{});
        // End Aggregation Example 1

        auto count = std::distance(cursor.begin(), cursor.end());
        if (count != 0L) {
            throw std::logic_error("wrong count in example 1");
        }
    }

    {
        // Start Aggregation Example 2
        using namespace bsoncxx::builder::basic;

        mongocxx::pipeline p{};
        p.unwind("$items");
        p.match(make_document(kvp("items.fruit", "banana")));
        p.group(make_document(
                kvp("_id", make_document(kvp("day", make_document(kvp("$dayOfWeek", "$date"))))),
                kvp("count", make_document(kvp("$sum", "$items.quantity")))));
        p.project(make_document(
                kvp("dayOfWeek", "$_id.day"), kvp("numberSold", "$count"), kvp("_id", 0)));
        p.sort(make_document(kvp("numberSold", 1)));

        auto cursor = db["sales"].aggregate(p, mongocxx::options::aggregate{});
        // End Aggregation Example 2

        auto count = std::distance(cursor.begin(), cursor.end());
        if (count != 0L) {
            throw std::logic_error("wrong count in example 2");
        }
    }

    {
        // Start Aggregation Example 3
        using namespace bsoncxx::builder::basic;

        mongocxx::pipeline p{};
        p.unwind("$items");
        p.group(make_document(
                kvp("_id", make_document(kvp("day", make_document(kvp("$dayOfWeek", "$date"))))),
                kvp("items_sold", make_document(kvp("$sum", "$items.quantity"))),
                kvp("revenue",
                    make_document(
                            kvp("$sum",
                                make_document(
                                        kvp("$multiply", make_array("$items.quantity", "$items.price"))))))));
        p.project(make_document(
                kvp("day", "$_id.day"),
                kvp("revenue", 1),
                kvp("items_sold", 1),
                kvp("discount",
                    make_document(
                            kvp("$cond",
                                make_document(
                                        kvp("if", make_document(kvp("$lte", make_array("$revenue", 250)))),
                                        kvp("then", 25),
                                        kvp("else", 0)))))));
        auto cursor = db["sales"].aggregate(p, mongocxx::options::aggregate{});
        // End Aggregation Example 3

        auto count = std::distance(cursor.begin(), cursor.end());
        if (count != 0L) {
            throw std::logic_error("wrong count in example 3");
        }
    }

    {
        // Start Aggregation Example 4
        using namespace bsoncxx::builder::basic;

        mongocxx::pipeline p{};
        p.lookup(make_document(
                kvp("from", "air_airlines"),
                kvp("let", make_document(kvp("constituents", "$airlines"))),
                kvp("pipeline",
                    make_array(make_document(
                            kvp("$match",
                                make_document(kvp(
                                        "$expr",
                                        make_document(kvp("$in", make_array("$name", "$$constituents"))))))))),
                kvp("as", "airlines")));
        p.project(make_document(
                kvp("_id", 0),
                kvp("name", 1),
                kvp("airlines",
                    make_document(kvp(
                            "$filter",
                            make_document(kvp("input", "$airlines"),
                                          kvp("as", "airline"),
                                          kvp("cond",
                                              make_document(kvp(
                                                      "$eq", make_array("$$airline.country", "Canada"))))))))));

        auto cursor = db["air_alliances"].aggregate(p, mongocxx::options::aggregate{});
        // End Aggregation Example 4

        // TODO: Remove version-check (CXX-1547)
        // This example uses syntax added in mongo version 3.6. Our CI
        // tooling runs tests with mongo version 3.4, so this example
        // fails with a query exception. CXX-1547 tracks removing this
        // version check once CI tooling uses a later version of the server.
        if (get_server_version(client) >= "3.6") {
            auto count = std::distance(cursor.begin(), cursor.end());
            if (count != 0L) {
                throw std::logic_error("wrong count in example 4");
            }
        }
    }
}

int main()
{
    // The mongocxx::instance constructor and destructor initialize and shut down the driver,
    // respectively. Therefore, a mongocxx::instance must be created before using the driver and
    // must remain alive for as long as the driver is in use.
    const mongocxx::instance inst{};

    const mongocxx::client conn{mongocxx::uri{}};
    auto const db = conn["documentation_examples"];

    try {
        aggregation_examples(conn, db);
    } catch (const std::logic_error &e) {
        std::cerr << e.what() << std::endl;
        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}
